Methoxypolyethylene glycol thioester chelate and uses thereof

ABSTRACT

The present invention is directed generally to protecting cells, tissues and organs against the damaging effects of ionizing or other damaging agents associated with radiation or chemotherapy, or degenerative diseases or processes of various organs that elicit the production of free radicals or oxidants such as peroxides, superoxide anions, hydroxyl radicals or nitric oxides, or heavy metal cations. More particularly, the present invention is concerned with methoxypolyethylene glycol thioester chelate methyl esters that are useful as protectors against tissue damage by penetrating the cell membrane to remove electrons from free radical oxidants and remove heavy metals that may react with peroxides to produce the reactive hydroxyl radical, or remove Ca ++  that may be released from organelles. These chelate esters will also have utility in reducing intraocular pressure in glaucoma patients.

FIELD OF INVENTION

The present invention is directed generally to protecting cells,tissues, organs, and organisms including humans against the damagingeffects of ionizing agents or radicals associated with radiation,chemotherapy, or with diseases or processes that result in cell damage,in which the production of free radical oxidants such as peroxides,superoxide anions, hydroxyl radicals or nitric oxides, or heavy metalcations is implicated. More particularly, the present invention isdirected to novel methoxypolyethylene glycol thioester chelate esters,and to methods of using them as bioprotectants in normal or diseasedhumans, animals or plants, in organ transplantation and cell and tissuestorage or preservation, and reduction of chemotoxicity, alone or asadjuvants with other agents or therapies. These chelate esters also willhave utility in reducing intraocular pressure in glaucoma patients.

BACKGROUND OF INVENTION

In humans, exposure to ionizing radiation occurs through natural sources(such as ultraviolet or other electromagnetic radiation or cosmicradiation from the sun, stars or terrestrial radioactive sources in theearth's crust) or from various man-made sources. The primary exposurefrom man-made sources comes from diagnostic x-rays and radionuclidestudies, dental x-rays, and therapeutic techniques (such as anticancerradiotherapy) or to a lesser extent due to fallout from atmosphericatomic weapons testing, nuclear power plants and through occupationalexposure. Ionizing radiation has an adverse effect on cells and tissues,primarily through cytotoxic effects. A major way in which most forms ofionizing radiation damages biomolecules and cells is through a processcalled indirect action involving an interaction with water to producetoxic active oxygen species (OH·, ·O²⁻, or H₂O₂). A second mechanism,called direct action, involves direct effects on DNA.

Diminution of the deleterious effects of ionizing radiation bychemoprotection would be important to a number of diverse groups,including the general population exposed to cosmic and terrestrialirradiation, to patients given diagnostic and dental x-rays, to workersexposed to irradiation, to groups exposed to radiation through accidentsor acts of terrorism, to astronauts and airline personnel exposed to“extra” cosmic irradiation, and to patients given radiation to treatcancer. Approximately 60% of all cancer patients receive radiation aspart of their therapy, and the harm to the normal tissues often limitsthe radiation dose which can be administered to the tumor. With regardto ultraviolet radiation, the increasing prevalence of melanomas,pterygium and cataracts suggest the necessity of prophylactic measuresto reduce these problems.

Evidence is accumulating that the etiology of many degenerative diseasesthat afflict humanity includes free radical reactions. Examples of suchdegenerative diseases include atherosclerosis, cancer, inflammatoryjoint disease, arthritis, autoimmune diseases, asthma, diabetes, seniledementia, Alzheimer's disease, Parkinson's disease, multiple sclerosis,muscular dystrophy, ischemia, stroke, congestive heart failure anddegenerative eye diseases. The process of biological ageing might alsohave a free radical element. Most free radical damage to cells involvesoxygen free radicals or, more generally, activated oxygen species, whichinclude non-radical species such as singlet oxygen and hydrogen peroxideas well as free radicals.

The eye is one organ with intense activated oxygen species activity, andit requires high levels of antioxidants to protect its unsaturated fattyacids. Glaucoma is an example of a degenerative disease of the eye thatcan lead to retinal cell death. Glaucoma is a widespread ocular diseaseof unknown etiology that can lead to eventual blindness due to gradualloss of retinal ganglionic cells (RGC). The majority of glaucomapatients have elevated intraocular pressure (IOP), and drugs capable oflowering IOP, including beta adrenergic blockers, prostanoids,cannabinoids and carbonic anhydrase inhibitors, are used clinically toreduce the impact of the disease. A significant percentage of glaucomapatients, however, do not demonstrate elevated IOP, but still showgradual reduction in ocular function due to retinal cell death.Recently, attention has focused on attempts to use neuroprotectiveagents to increase the survival of the retinal cells, a strategy thatshould be effective in all glaucoma patients.

It is now evident that ganglion cells are dependent on a variety ofeurotrophins, but primarily on brain-derived neurotrophic factor (BDNF).An adult ganglion cell takes up secreted BDNF from its respective targetneuron and transports it along its axon back to the cell body in theretina. Glaucoma is now thought to block this retrograde flow of BDNF byblocking axoplasmic transport at the site of the lamina cribrosa(Nickells R W., J. Glaucoma 1996; 5:345-356). It is not precisely knownhow long a ganglion cell can survive without its BDNF supply, but testsconducted in culture suggest that it is only a matter of days. Oneobvious neuroprotective strategy that has been considered for glaucomatreatment is to provide a different source of BDNF for the ganglioncells. Another damaging stimulus associated with glaucoma is the releaseof excitotoxins. These molecules are actually excitatory amino acids,such as glutamate, that are normally used by neurons asneurotransmitters. At high local concentrations, however, these normallybenign molecules activate a highly toxic response in nearby cells (hencethe derivation of the word “excitotoxin”). Like neurotrophins,excitotoxins interact with receptors on the cell surface. There arethree known sub-types of glutamate receptors found on neurons, but theone that appears to play the biggest role in the excitotoxic effect isthe N-methyl-D-aspartate (NMDA) receptor. Elevated levels of glutamatehave been detected in the vitreous of both human glaucoma patients andmonkeys with experimental glaucoma (Dreyer E B, Zurakowski D, Schumer RA, Podos S M, Lipton S A., Arch. Opthalmol. 1996; 114:299-305).

Transition metals such as iron and copper are known to generatecytotoxic free radicals, whereas iron-regulating proteins such astransferrin, ceruloplasmin, and ferritin have been shown to act asanti-oxidants, counteracting the toxic effects of these metals. Iron andcopper cations are released from tissues during ischemia and inassociation with a variety of disease processes. Tissues deprived ofblood and oxygen undergo ischemic necrosis or infarction with possibleirreversible organ damage. Even if the flow of blood and oxygen isrestored to the organ or tissue (reperfusion), the organ does notimmediately return to the normal pre-ischemic state. Post-ischemicdysfunction may be due to the generation of oxygen free radicals in thestunned organ. The re-entry of neutrophils during reperfusion can createfree radical damage due to the hyper-reactivity of leukocytes. Iron andcopper cations are known to catalyze hydroxy free radical formation. Thechelator ethylenediaminetetraacetic acid (EDTA) is known to reduce lipidperoxidation from ionizing radiation. (Ayene-S I; Srivastava-P N Int. J.Radiat. Biol. Relat. Stud. Phys. Chem. Med. 1985 August; 48(2):197-205). Providing anti-oxidants and reducing equivalents toischemically stressed tissue allows recovery of the mitochondria, whichis crucial in restoring normal calcium homeostasis and tissue function.

It is further known that metal cations, such as Ca⁺⁺, that are not firsttransition series elements perform important functions in the body, butmay also be involved in a number of pathogenic processes, such ascalcium overload of the heart that occurs during ischemia andreperfusion. Such metal cations can compete with cations of firsttransition series elements for chelation by a chelator that has a highaffinity for Ca⁺⁺, and thereby interfere with the chelation of firsttransition series cations by the chelator. Moreover, chelation ofcations such as Ca⁺⁺ can impair the normal functions of these cations inthe body. Therefore, the use of chelators must be tempered with theknowledge of the role of various cations in the disease process to betreated and the selection of specific chelator affinities to remove theoffending cations without creating additional ionic imbalances.

Numerous attempts have been made to reduce normal tissue damage whilestill delivering effective therapeutic doses of ionizing radiation tothe cancerous tissue. These techniques include brachytherapy,fractionated and hyperfractionated dosing, complicated dose schedulingand delivery systems, and high voltage therapy with a linearaccelerator. However, such techniques can, at best, only attempt tostrike a balance between the beneficial effects of killing the cancercells and undesirable effects of the radiation to the normal tissues.There is much room for improvement in the therapeutic ratio, which isthe ratio of a measure of damage to the tumor divided by the damage tothe normal tissues.

Attempts to mitigate the catalytic effectiveness of iron and coppercations by administering iron chelating siderophores such asdeferoxamine to form complexes with these cations have not beenunequivocally successful in inhibiting tissue damage from hydroxy freeradicals in vivo. Siderophores such as deferoxamine are poor chelatorsfor copper cations. Although present in the body in much lowerconcentrations than iron, copper is far more active than iron incatalyzing hydroxyl radical formation.

Polyethylene glycol (PEG) and polyethylene glycol monomethyl ether (MP)have also been found to reduce tissue injury, although the mechanism isobscure. PEG is an amphiphilic polymer H(OCH₂ CH₂)_(n)OH that consistsof a mixture of homologs with a range of similar molecular weights.Thus, for example, MP 350 possesses an average molecular weight 350, andconsists of a mixture of homologs with n=4 to 9, and a median n=7. Thelower molecular weight polymers PEG 200-600 are absorbed through thegastrointestinal tract when ingested orally and excreted unchanged inthe urine. PEG is absorbed along with water directly through theintestinal mucosal cell membrane.

PEG 200-600, being nontoxic and biologically inert, has often been usedas a vehicle for administration of drugs insoluble in water. In severalinvestigations, the PEG vehicle alone was empirically found to exhibitsignificant biological activity, leading to further studies of lowmolecular weight PEG. For example, PEG 400, when given intraperitoneally(IP) either before or shortly after x-irradiation of mice, conferredsignificant protection against lethality and morbidity (Shaeffer andSchellenberg, Int. J. Radiat. Oncol. Biol. Phys., 10:2329, 1984;Shaeffer, et al., Radiat. Res., 107:125, 1986). PEG 300 IP was shown toreduce the CNS sequelae of experimental concussive brain injury(Clifton, et al., J. Neurotrauma, 6:71, 1989).

PEG with a molecular weight around 400 is thus a uniquely nontoxicsubstance that exhibits a protective effect against injury to tissues.However, PEG with a molecular weight greater than 700 is poorly absorbedthrough the GI tract. The mechanism of the protective action of lowermolecular weight PEG has not been established, but probably involvesinteraction of PEG with the surface of lipid membranes or proteincomponents. PEG aggregates near cell membranes, reduces water polarityat membrane surfaces, and increases hydrophobic interactions (Hoekstra,et al., J. Biol. Chem., 264:6786, 1989).

It is known that certain MP chelates can be effective iron chelators.For example, it is known that MP can be linked with iminodiacetateterminus (MIDA). Other chelates modified with MP include MP550-deferoxamine (ferrioxamine), prepared by reacting MP molecularweight 550 with carbonyldiimidazole, followed by reaction of theresulting imidazolecarbonyl ester with deferoxamine base, forming aurethane linkage. The material was produced as a chelate for gadolinium,to be used as a renal magnetic resonance contrast agent (Duewell, etal., Invest. Radiol., 26:50, 1991). Deferoxamine is known to be aneffective chelator for ferric iron.

MIDA can be prepared by converting MP 350 to the chloride by reactionwith thionyl chloride (Bueckmann et al., Biotechnology & AppliedBiochem., 9:258-268, 1987), and to the iminodiacetate by reaction of thechloride with sodium iminodiacetate (Wuenschell et al., J. Chromatog.543: 345-354, 1991). The methyl ester can be prepared with methanolicHCl. However, alternative MP chelates, which are more effectivechelators and are non-toxic, have been sought.

U.S. Pat. No. 6,020,373 discloses that the polyethylene glycol linked toa chelate methyl ester was a very effective protectant against radiationdamage and doxorubicin toxicity in animal models. The well-knownradioprotectant amifostine, S-2-[3-aminopropylamino]ethylphosphorothioate (WR-2721, Ethyol), that possesses a potentialthiol, has been used extensively in the clinic for protection of normaltissues in radiotherapy and chemotherapy (Wasserman, T. H., Seminars inOncology 21(5 Supp. 11): 21-25, 1994), but its effectiveness is limited.Sulfhydryl compounds, such as cysteine and cysteamine, have been knownto provide radiation protection in animals. Thiol groups scavengeradiation-produced free radicals by donating a hydrogen atom to damagedmolecules. Despite extensive efforts to develop more effectiveprotective agents, no thiol-based radioprotector has been found to besignificantly better than cysteamine. Moreover, the use of thiol drugsto protect against radiation damage has been limited due to the toxicityof such compounds. Further, the use of esters of polar drugs tofacilitate penetration into cells has been reported (Vos et al, Int. J.Radiat. Biol. Relat. Stud. 53:273-81, 1988).

A need clearly exists, therefore, for improved compositions and methodscapable of protecting cells, tissues and organs against the damagingeffects of an ionizing agent associated with radiation or chemotherapy,or with disease or other states in which the production of free radicaloxidants such as peroxides, superoxide anions, hydroxyl radical ornitric oxide, or heavy metal cations is implicated.

SUMMARY OF THE INVENTION

The present invention provides compositions and methods capable ofprotecting cells, tissues and organs against the damaging effects ofionizing or other damaging agents associated with radiation orchemotherapy, or degenerative diseases of various organs, characterizedin that they elicit the production of free radicals or oxidants such asperoxides, superoxide anions, hydroxyl radicals or nitric oxides, orheavy metal cations. More particularly, the present invention isconcerned with methoxypolyethylene glycol thioester chelate methylesters that are useful as protectors against tissue damage bypenetrating the cell membrane to remove electrons from free radicaloxidants and remove heavy metals that may react with peroxides toproduce the reactive hydroxyl radical, or remove Ca⁺⁺ that may bereleased from organelles. The present invention would also be useful inreducing the elevated intraocular pressure found in various forms ofglaucoma.

Accordingly, the present invention relates to a methoxypolyethyleneglycol thioester compound of formula (I):

wherein one R₁ is formula (II)

each of the remaining R₁ is selected from formula (II) or from the groupconsisting of —CH₂COOH, —CH₂COO⁻Na⁺, —CH₂COO⁻Ca⁺⁺/2, —CH₂COOCH₃,—CH₂COOC₂H₅, and—CH₂COOC₃H₇; a is 0 to 6; each b is independently 0 to18; each c is independently 3 to 10; and d is independently 1 to 3.

One embodiment of the present invention is the compound of formula (I)wherein a is 0, each b is 0, each c is independently 3 to 10, d is 1,and three R₁s are —CH₂COOCH₃. In one example the present invention isthe compound of formula (I) wherein a is 0, each b is 0, each c isindependently 7 or 8, d is 1, and three R₁s are —CH₂COOCH₃.

In another embodiment of the present invention is the compound offormula (I) wherein a is 1, each b is 0, each c is independently 3 to10, d is 1, and four R₁s are —CH₂COOCH₃. In one example the presentinvention is the compound of formula (I) wherein a is 1, each b is 0,each c is independently 7 or 8, d is 1, and four R₁s are —CH₂COOCH₃.

More specifically, the present invention relates to compound having thefollowing formula:

wherein n=3 to 10.

In another embodiment the present invention relates to compound havingthe following formula:

wherein n=3 to 10.

In one embodiment of the present invention, the compound of formula (I)is capable of extracting electrons. In one embodiment of the presentinvention, the compound of formula (I) is capable of forming chelateswith heavy metals or Ca⁺⁺.

The present invention is also directed to a pharmaceutical compositioncomprising the compound of formula (I) and at least one of apharmaceutically acceptable carrier or a pharmaceutically acceptableadjuvant. In one embodiment, the present invention is directed to apharmaceutical composition comprising the compound of formula (I) or apharmaceutically acceptable salt or solvate thereof, and, optionally, atleast one therapeutic agent.

The present invention is further directed to a method for preventingtissue damage resulting from exposure to radiation in a patient in needthereof comprising administering to the patient a therapeuticallyeffective amount of the compound of formula (I).

In one embodiment, the present invention is directed to a method forpreventing degenerative disease resulting from free radical oxidants ina patient in need thereof comprising administering to the patient atherapeutically effective amount of the compound of formula (I), whereinfree radical oxidants comprises peroxides, superoxide anions, hydroxylradical, and nitric oxide.

In another embodiment, the present invention is directed to a method fortreating retinal cell death resulting from glaucoma in a patient in needthereof comprising administering to the patient a therapeuticallyeffective amount of the composition comprising the compound of formula(I) and at least one of a pharmaceutically acceptable carrier or apharmaceutically acceptable adjuvant.

In yet another embodiment, the present invention is directed to a methodfor extracting electrons from free radical oxidants in a cell in needthereof comprising administering an effective amount of the compound offormula (I), wherein free radical oxidants comprises peroxides,superoxide anions, hydroxyl radical, and nitric oxide.

In one example, the present invention is directed to a method forpreventing catalysis of free radical oxidants formation by heavy metalsin a cell in need thereof comprising administering an effective amountof the compound of formula (I), wherein free radical oxidants comprisesperoxides, superoxide anions, hydroxyl radical, and nitric oxide,wherein the compound is capable of forming chelates with heavy metals.

The present invention is also directed to a kit comprising at least onecompound of formula (I), or a pharmaceutically acceptable salt orsolvate thereof, and instruction for use thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary process by which the drug is hydrolyzedto MPthiol which removes electrons from free radical oxidants while thechelate removes heavy metals produced by cell damage.

FIG. 2 illustrates a representative mass spectrum of methoxypolyethleneglycol thiol coupled with EDTA methyl triester (MPSEDE).

FIG. 3 illustrates the effectiveness of MPthiol compounds asradioprotectant.

FIG. 4 demonstrates penetration of MPDTE into the globe in rats upontopical ocular administration.

FIG. 5 illustrates the dose response of topical ocular administration ofMPDTE.

FIG. 6 illustrates the dose response of topical ocular administration ofMPSEDE.

FIG. 7 illustrates the average dose response of topical ocularadministration of 30 mM MP compounds.

FIG. 8 illustrates the effect of increasing concentration of MPSEDE andMPDTE on intraocular pressure.

FIG. 9 illustrates comparison of the IOP reduction caused by MPDTE withknown radioprotectant.

FIG. 10 illustrates comparison of the IOP reduction caused by MPDTE, MP,and DTE.

FIG. 11 illustrates a representative A-Wave component ofelectroretinogram measurements following co-administration of MPcompounds with NMDA.

FIG. 12 illustrates a representative B-Wave component ofelectroretinogram measurements following co-administration of MPGcompounds with NMDA.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides novel compounds for use in protectingcells, tissues, organs, and organisms against the damaging effects ofionizing agents associated with radiation or chemotherapy, ordegenerative diseases of various organs, that elicits the production offree radicals, superoxide anions, or heavy metal cations. In one aspect,the present invention is directed to a combination of a potential thiolwith a potential chelate, together with the amphiphilic polyethyleneglycol tail that facilitates transport into cells, to allow for a dualprotective mechanism against free radical damage to cells.

In one aspect, the present invention is directed to novel amphiphiliccell-penetrating methoxypolyethylene glycols (MP) with an average weightof 200 to 600, more preferably 300 to 450, and most preferably 350 (MP350), which are modified by chemically attaching chelating groups ontothe non-methyl end of the polymer by a thioester linkage.

Exemplary chelating groups that can be used to modify themethoxypolyethylene glycols of the invention includeethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaaceticacid (DTPA) and similar chelating groups formed, for example, byreaction of bromoacetic acid or derivatives to triethylenetetramine andother higher homologs containing ethylenamine linkages, or otherchelating groups such as cyclohexanediaminetetraacetic acid and ethyleneglycol aminoethyl ether tetraacetic acid (EGTA).

The compounds of the present invention generally have the followingformula:

wherein one R₁ is formula (II)

-   -   each of the remaining R₁ is selected from formula (II) or from        the group consisting of —CH₂COOH, —CH₂COO⁻Na⁺ or other        monovalent ion, —CH₂COO⁻Ca⁺⁺/2 or other divalent or multivalent        ion, —CH₂COOCH₃, —CH₂COOC₂H₅, and —CH₂COOC₃H₇;    -   a is 0 to 6; each b is independently 0 to 18; each c is        independently 3 to 10; and d is independently 1 to 3.

One embodiment of the present invention is the compound of formula (I)wherein a is 0, each b is 0, each c is independently 3 to 10, preferably7, d is 1, one R₁ is formula (II), and three R₁s are —CH₂COOCH₃.

Another embodiment of the present invention is the compound of formula(I) wherein a is 1, each b is 0, each c is independently 3 to 10,preferably 7, d is 1, one R₁ is formula (II), and remaining R₁s are—CH₂COOCH₃.

In one example, compound of the present invention is methoxypolyethleneglycol thioester of ethylenediaminetetraacetic acid methyl triester(MPSEDE) having the following formula:

wherein n=3 to 10, preferably 7.

In another example, compound of the present invention ismethoxypolyethlene glycol thioester of diethylenetriaminepentaaceticacid methyl tetraester having the following formula

wherein n=3 to 10, preferably 7.

The present invention further provides a process for the preparation ofa compound of formula (I) as defined above which comprises the steps offirst converting MP to the chloride by reaction with thionyl chloride(Bueckmann et al., Biotechnology & Applied Biochem., 9:258-268, 1987),and then to a thiol (MPthiol) by reaction of the chloride with thiourea(Urquhart et al Organic Syntheses Coll. Vol 3; Homing, E. C.; Ed.;Wiley, N.Y., 1955; pp 363-365). MPthiol was coupled to the chelators asa thioester using carbonyldiimidazole as coupling agent withdimethylformamide solvent (Gais, Angew. Chem. Int. Ed. 16:244-246,1977), followed by methyl esterification of the other carboxyl groupswith methanol and carbonyldiimidazole. Methoxypolyethlene glycolthioester of ethylenediamine tetraacetic acid (MPSEDE) andmethoxypolyethlene glycol thioester of diethylenetriamine pentaaceticacid (MPSDTE) can be prepared in the same manner by coupling the MPthiolwith EDTA and DTPA respectively.

The compounds of formula (I) above may be converted to apharmaceutically acceptable salt or solvate thereof, preferably an acidaddition salt such as a hydrochloride, hydrobromide, phosphate, acetate,fumarate, maleate, tartrate, citrate, oxalate, methanesulphonate orparatoluenesulphonate.

Compounds of formula (I) may exist in stereoisomeric forms. It will beunderstood that the invention encompasses the use of all geometric andoptical isomers of the compounds of formula (I) and mixtures thereofincluding racemates. The use of tautomers and mixtures thereof alsoforms a contemplated aspect of the present invention.

Compounds of formula (I) may include other chelators or reducing groups,such as BAPTA, TPEN (tetrakis-(2-pyridylmethyl)ethylenediamine), calceinas chelators and NADH and NAD(P)H as reducing groups.

A particularly important feature of the compounds of the invention istheir ability to penetrate the cell membrane. In one embodiment, thepresent invention is directed to novel amphiphilic cell-penetratingmethoxypolyethylene glycols (MP) with an average weight of 200 to 600,more preferably 300 to 450, and most preferably 350 (MP 350), which aremodified by chemically attaching chelating groups onto the non-methylend of the polymer by linkages that include functional groups such asselenium, sulfoxide, reductones containing the enediol group (such asascorbic acid and dihydroxymaleic acid), hydroroquinines,dihydropyridines, tetrasubstituted hydroquinone ethers including thetocopherol ring system, dithiols including dihydrolipoic acid, indoles,and conjugated polyenes including carotenoids that result inradical-reducing agents. Other chelates may include chelates withcarbamate groups in place of carboxyl including deferoxamine, andheterocyclic amines including orthophenanthroline, 1,1-dipyridyl, and8-hydroxyquinoline. In one example, compounds of the present inventionincludes MP thioesters of cyclohexanediaminetetraacetic acid andethylene glycol aminoethyl ether tetraacetic acid (EGTA), which aresynthesized by substituting EDTA with cyclohexanediaminetetraacetic acidor EGTA during the step involving coupling MPthiol to a chelate withcarbonyldiimidazole.

While not intending to be bound by any particular theory of action, thisability to penetrate the cell membrane is believed to be the result ofnon-polarity conferred by the amphiphilic MP and the nonpolar estergroups, possibly through membrane channels used for nonpolarmetabolites, followed by rapid activation by intracellular esterases tothe thiol and the active chelate. The thiol is thought effective inremoving electrons from free radical oxidants such as peroxides,superoxide, hydroxyl radical, or nitric oxide, with formation of thedisulfide, while the chelate is believed to remove heavy metals, such asFe⁺⁺, Fe⁺⁺⁺ or Cu⁺⁺, produced by cell damage, and that may react withperoxides to produce the reactive hydroxyl radical, or remove Ca⁺⁺ thatmay be released from organelles. The compounds of the invention thushave the capability of protecting cells by two different mechanisms.This process is illustrated in FIG. 1.

In a further aspect, the present invention provides the use of acompound of formula (I), or a pharmaceutically acceptable salt orsolvate thereof, in the manufacture of a medicament for use in therapy.It is understood that the medicament may include other components orpharmaceutically acceptable adjuvant with different or similarmechanisms of action permitting a broader scope of prophylaxis ortherapeutic effect than the MP ester or salt alone. The term “adjuvant”is intended to be construed as an ingredient that modifies the action ofthe principal ingredient or an ingredient that enhances theeffectiveness of medical treatment or an ingredient that enhances theimmune response to an antigen

In the context of the present specification, the term “therapy” alsoincludes “prophylaxis” unless there are specific indications to thecontrary. The terms “therapeutic” and “therapeutically” are intended tobe construed accordingly.

The invention provides a safe and effective method of treatingAlzheimer's in a patient suffering from, or at risk of, thisdebilitating neurodegenerative disease, which comprises administering toa patient in need thereof a therapeutically effective amount of acompound of formula (I), or a pharmaceutically acceptable salt orsolvate thereof.

The invention also provides a safe and effective method of treatingParkinson's disease in a patient suffering from, or at risk of, saiddisease, which comprises administering to the patient a therapeuticallyeffective amount of a compound of formula (I), or a pharmaceuticallyacceptable salt or solvate thereof.

The invention also provides a safe and effective method of treatingmultiple sclerosis (MS) in a patient suffering from, or at risk of, saiddisease, which comprises administering to the patient a therapeuticallyeffective amount of a compound of formula (I), or a pharmaceuticallyacceptable salt or solvate thereof.

The invention still further provides a safe and effective method oftreating muscular dystrophy (MD) in a patient suffering from, or at riskof, said disease, which comprises administering to the patient atherapeutically effective amount of a compound of formula (I), or apharmaceutically acceptable salt or solvate thereof.

The invention provides a safe and effective method of treating radiationdamage and the prevention of radiation-related cancers in a patient inneed thereof by administering to the patient a therapeutically effectiveamount of a compound of formula (I), a pharmaceutically acceptable saltor solvate thereof, or a pharmaceutically acceptable adjuvant thereof.The source of radiation may be electromagnetic, including visible orultraviolet light, or nuclear, including alpha, beta, gamma, or cosmicradiation. The types of damage may include, but is not limited to,various forms of dermatological damage, such as sunburn, age spots andmelanomas, as well as internal cell loss, cyst formation, neuropathiesand various types of benign and malignant tumors.

The invention provides a safe and effective method of treating toxicityto normal tissues from chemotherapy in a patient in need thereof, orinadvertent or intentional administration of chemical agents having afree radical and/or heavy metal toxicological component, byadministering to the patient a therapeutically effective amount of acompound of formula (I), a pharmaceutically acceptable salt or solvatethereof, or a pharmaceutically acceptable adjuvant thereof and one ormore chemical agents having a free radical and/or heavy metaltoxicological components. The compound of formula (I) may beadministered before, during or after administration of the chemicalagents having a free radical and/or heavy metal toxicologicalcomponents. The invention is useful for reducing the toxicity ofchemical agents having a free radical and/or heavy metal toxicologicalcomponents including fluoropyrimidines, pyrimidine nucleosides, purines,platinum analogues, antroacyclines, podophyllotoxins, camptothecins,hormones and hormone analogues, enzymes, proteins and antibodies, vincaalkaloids, taxanes, and the like. While the present method for reducingtoxicity is applicable for any chemotherapeutic agent some exemplaryones are irinotecan, FU, taxol, cisplatin adriamycin, oxaliplatin,cyclophasphamide, EGF and VGF inhibitors, acemannan, acetaminophen,aclarubicin, aldesleukin, alemtuzumab, alitretinoin, altretamine,amifostine, aminolevulinic acid, amrubicin, amsacrine, anagrelide,anastrozole, ANCER, ancestim, ARGLABIN, arsenic trioxide, BAM 002(Novelos), bexarotene, bicalutamide, broxuridine, capecitabine,celmoleukin, cetrorelix, cladribine, clotrimazole, cytarabine ocfosfate,DA 3030 (Dong-A), daclizumab, denileukin diftitox, deslorelin,dexrazoxane, dilazep, docetaxel, docosanol, doxercalciferol,doxifluridine, doxorubicin, bromocriptine, carmustine, cytarabine,fluorouracil, HIT diclofenac, interferon alfa, daunorubicin, tretinoin,edelfosine, edrecolomab, eflomithine, emitefur, epirubicin, epoetinbeta, etoposide phosphate, exemestane, exisulind, fadrozole, filgrastim,finasteride, fludarabine phosphate, formestane, fotemustine, galliumnitrate, gemcitabine, gemtuzumab zogamicin, gimeracil/oteracil/tegafurcombination, glycopine, goserelin, heptaplatin, human chorionicgonadotropin, human fetal alpha fetoprotein, ibandronic acid,idarubicin, (imiquimod, interferon alfa, interferon alfa, natural,interferon alfa-2, interferon alfa-2a, interferon alfa-2b, interferonalfa-N1, interferon alfa-n3, interferon alfacon-1, interferon alpha,natural, interferon beta, interferon beta-1a, interferon beta-1b,interferon gamma, natural interferon gamma-1a, interferon gamma-1b,interleukin-1 beta, iobenguane, irinotecan, irsogladine, lanreotide, LC9018 (Yakult), leflunomide, lenograstim, lentinan sulfate, letrozole,leukocyte alpha interferon, leuprorelin, levamisole+fluorouracil,liarozole, lobaplatin, lonidamine, lovastatin, masoprocol, melarsoprol,metoclopramide, mifepristone, miltefosine, mirimostim, mismatched doublestranded RNA, mitoguazone, mitolactol, mitoxantrone, molgramostim,nafarelin, naloxone+pentazocine, nartograstim, nedaplatin, nilutamide,noscapine, novel erythropoiesis stimulating protein, NSC 631570octreotide, oprelvekin, osaterone, oxaliplatin, paclitaxel, pamidronicacid, pegaspargase, peginterferon alfa-2b, pentosan polysulfate sodium,pentostatin, picibanil, pirarubicin, rabbit antithymocyte polyclonalantibody, polyethylene glycol interferon alfa-2a, porfimer sodium,raloxifene, raltitrexed, rasburicase, rhenium Re 186 etidronate, RIIretinamide, rituximab, romurtide, samarium (153 Sm) lexidronam,sargramostim, sizofuran, sobuzoxane, sonermin, strontium-89 chloride,suramin, tasonermin, tazarotene, tegafur, temoporfin, temozolomide,teniposide, tetrachlorodecaoxide, thalidomide, thymalfasin, thyrotropinalfa, topotecan, toremifene, tositumomab-iodine 131, trastuzumab,treosulfan, tretinoin, trilostane, trimetrexate, triptorelin, tumornecrosis factor alpha, natural, ubenimex, bladder cancer vaccine,Maruyama vaccine, melanoma lysate vaccine, valrubicin, verteporfin,vinorelbine, VIRULIZIN, zinostatin stimalamer, or zoledronic acid;abarelix; AE 941 (Aeterna), ambamustine, antisense oligonucleotide,bcl-2 (Genta), APC 8015 (Dendreon), cetuximab, decitabine,dexaminoglutethimide, diaziquone, EL 532 (Elan), EM 800 (Endorecherche),eniluracil, etanidazole, fenretinide, filgrastim SDO1 (Amgen),fulvestrant, galocitabine, gastrin 17 immunogen, HLA-B7 gene therapy(Vical), granulocyte macrophage colony stimulating factor, histaminedihydrochloride, ibritumomab tiuxetan, ilomastat, IM 862 (Cytran),interleukin-2, iproxifene, LDI 200 (Milkhaus), leridistim, lintuzumab,CA 125 MAb (Biomira), cancer MAb (Japan Pharmaceutical Development),HER-2 and Fc MAb (Medarex), idiotypic 105AD7 MAb (CRC Technology),idiotypic CEA MAb (Trilex), LYM-1-iodine 131 MAb (Techniclone),polymorphic epithelial mucin-yttrium 90 MAb (Antisoma), marimastat,menogaril, mitumomab, motexafin gadolinium, MX 6 (Galderma), nelarabine,nolatrexed, P 30 protein, pegvisomant, pemetrexed, porfiromycin,prinomastat, RL 0903 (Shire), rubitecan, satraplatin, sodiumphenylacetate, sparfosic acid, SRL 172 (SR Pharma), SU 5416 (SUGEN), SU6668 (SUGEN), TA 077 (Tanabe), tetrathiomolybdate, thaliblastine,thrombopoietin, tin ethyl etiopurpurin, tirapazamine, cancer vaccine(Biomira), melanoma vaccine (New York University), melanoma vaccine(Sloan Kettering Institute), melanoma oncolysate vaccine (New YorkMedical College), viral melanoma cell lysates vaccine (Royal NewcastleHospital), or valspodar.

The invention provides a safe and effective method of treating ischemiain a patient suffering from, or at risk of, said disease, whichcomprises administering to the patient a therapeutically effectiveamount of a compound of formula (I), or a pharmaceutically acceptablesalt or solvate thereof.

The invention also provides a safe and effective method of treatingstroke in a patient suffering from, or at risk of, said disease, whichcomprises administering to the patient a therapeutically effectiveamount of a compound of formula (I), or a pharmaceutically acceptablesalt or solvate thereof.

The invention also provides a safe and effective method of treatingcongestive heart failure in a patient suffering from, or at risk of,said disease, which comprises administering to the patient atherapeutically effective amount of a compound of formula (I), or apharmaceutically acceptable salt or solvate thereof.

The invention still further provides a safe and effective method oftreating ocular diseases in a patient suffering from, or at risk of,said diseases, which comprises administering to the patient in needthereof a therapeutically effective amount of a compound of formula (I),or a pharmaceutically acceptable salt or solvate thereof. Other diseasescan include any presently known to medical science, including but notlimited to glaucoma, macular degeneration, cataracts, melanomas,pterygium, and the like.

The invention still further provides a safe and effective method oftreating neurodegenerative, rheumatological, arthritic or autoimmunediseases in a patient suffering from, or at risk of, said diseases,which comprises administering to the patient a therapeutically effectiveamount of a compound of formula (I), or a pharmaceutically acceptablesalt or solvate thereof. Other diseases can include any presently knownto medical science, including but not limited to various forms ofarthritis, Crohn's disease, fibromuscular dysplasia, and the like.

The invention provides a safe and effective method for cell, tissue ororgan preservation in a patient in need thereof by administering to thepatient a therapeutically effective amount of a compound of formula (I),or a pharmaceutically acceptable salt or solvate thereof.

The invention provides a safe and effective method for treatment orprevention of iron or other heavy metal or transition element toxicityin a patient in need thereof by administering to the patient atherapeutically effective amount of a compound of formula (I), or apharmaceutically acceptable salt or solvate thereof.

The invention provides a safe and effective method for protection ofisolated organs, tissue, cells including blood cells, sperm, plantcells, extracts, membranes, liposomes, proteins, carbohydrates, lipids,DNA or other natural or synthetic biological materials by including inthe medium a therapeutically effective amount of a compound of formula(I), or a pharmaceutically acceptable salt or solvate thereof.

The compounds of formula (I) and pharmaceutically acceptable salts andsolvates thereof may be used on their own but will generally beadministered in the form of a pharmaceutical composition in which theformula (I) compound/salt/solvate (active ingredient) is in associationwith a pharmaceutically acceptable adjuvant, diluent or carrier.Depending on the mode of administration, the pharmaceutical compositionwill preferably comprise from 0.05 to 99% w (percent by weight), morepreferably from 0.05 to 80% w, still more preferably from 0.10 to 70% w,and even more preferably from 0.10 to 50% w, of active ingredient, allpercentages by weight being based on total composition.

The present invention also provides a pharmaceutical compositioncomprising a compound of formula (I), or a pharmaceutically acceptablesalt, ester, or solvate thereof, as herein defined, in association witha pharmaceutically acceptable adjuvant, diluent or carrier.

The invention further provides a process for the preparation of apharmaceutical composition of the invention which comprises mixing acompound of formula (I), or a pharmaceutically acceptable salt, ester,or solvate thereof, as herein described, with a pharmaceuticallyacceptable adjuvant, diluent or carrier. The carrier(s) must be“acceptable” in the sense of being compatible with the other ingredientsof the formulation and not deleterious to the recipient thereof.

The pharmaceutical compositions may be administered topically (e.g., tothe lung and/or airways or to the skin or other epithelial surface) inthe form of solutions, suspensions, native or heptafluoroalkane aerosolsand dry powder formulations; or systemically, e.g., by oraladministration in the form of tablets, capsules, syrups, powders orgranules, or by parenteral administration in the form of solutions orsuspensions, or by subcutaneous administration or by vaginal or rectaladministration in the form of suppositories, or transdermally.

The compounds and compositions of the present invention can beadministered by any available and effective delivery system including,but not limited to, orally, bucally, within the ear or nasal passages,parenterally, by inhalation spray, by topical application, by injection,transdermally, vaginally or rectally (e.g., by the use of suppositories)in dosage unit formulations containing conventional nontoxicpharmaceutically acceptable carriers, adjuvants, and vehicles, asdesired. Parenteral includes subcutaneous injections, intravenous,intramuscular, intrasternal injection, or infusion techniques.

Transdermal compound administration, which is known to one skilled inthe art, involves the delivery of pharmaceutical compounds viapercutaneous passage of the compound into the systemic circulation ofthe patient. Topical administration can also involve the use oftransdermal administration such as transdermal patches or iontophoresisdevices. Other components can be incorporated into the transdermalpatches as well. For example, compositions and/or transdermal patchescan be formulated with one or more preservatives or bacteriostaticagents including, but not limited to, methyl hydroxybenzoate, propylhydroxybenzoate, chlorocresol, benzalkonium chloride, and the like.Dosage forms for topical administration of the compounds andcompositions can include creams, pastes, sprays, lotions, gels,ointments, eye drops, nose drops, ear drops, and the like. In suchdosage forms, the compositions of the invention can be mixed to formwhite, smooth, homogeneous, opaque cream or lotion with, for example,benzyl alcohol 1% or 2% (wt/wt) as a preservative, emulsifying wax,glycerin, isopropyl palmitate, lactic acid, purified water and sorbitolsolution. In addition, the compositions can contain polyethylene glycol400 which may function as solvent or absorption modifier. They can bemixed to form ointments with, for example, benzyl alcohol 2% (wt/wt) aspreservative, white petrolatum, emulsifying wax, and Tenox II (butylatedhydroxyanisole, propyl gallate, citric acid, propylene glycol). Wovenpads or rolls of bandaging material, e.g., gauze, can be impregnatedwith the compositions in solution, lotion, cream, ointment or other suchform can also be used for topical application. The compositions can alsobe applied topically using a transdermal system, such as one of anacrylic-based polymer adhesive with a resinous cross linking agentimpregnated with the composition and laminated to an impermeablebacking.

Solid dosage forms for oral administration can include capsules,tablets, effervescent tablets, chewable tablets, pills, powders,sachets, granules and gels. In such solid dosage forms, the activecompounds can be admixed with at least one inert diluent such assucrose, lactose or starch. Such dosage forms can also comprise, as innormal practice, additional substances other than inert diluents, e.g.,lubricating agents such as magnesium stearate. In the case of capsules,tablets, effervescent tablets, and pills, the dosage forms can alsocomprise buffering agents. Soft gelatin capsules can be prepared tocontain a mixture of the active compounds or compositions of the presentinvention and vegetable oil. Hard gelatin capsules can contain granulesof the active compound in combination with a solid, pulverulent carriersuch as lactose, saccharose, sorbitol, mannitol, potato starch, cornstarch, amylopectin, cellulose derivatives of gelatin. Tablets and pillscan be prepared with enteric coatings.

Liquid dosage forms for oral administration can include pharmaceuticallyacceptable emulsions, solutions, suspensions, syrups, and elixirscontaining inert diluents commonly used in the art, such as water. Suchcompositions can also comprise adjuvants, such as wetting agents,emulsifying and suspending agents, and sweetening, flavoring, andperfuming agents.

Suppositories for vaginal or rectal administration of the compounds andcompositions of the invention can be prepared by mixing the compounds orcompositions with a suitable nonirritating excipient such as cocoabutter and polyethylene glycols which are solid at room temperature butliquid at body temperature, such that they will melt and release thedrug.

Injectable preparations, for example, sterile injectable aqueous oroleaginous suspensions can be formulated according to the known artusing suitable dispersing agents, wetting agents and/or suspendingagents. The sterile injectable preparation can also be a sterileinjectable solution or suspension in a nontoxic parenterally acceptablediluent or solvent, for example, as a solution in 1,3-butanediol. Amongthe acceptable vehicles and solvents that can be used are water,Ringer's solution, and isotonic sodium chloride solution. Sterile fixedoils are also conventionally used as a solvent or suspending medium.

The compositions of the invention can further include conventionalexcipients, i.e., pharmaceutically acceptable organic or inorganiccarrier substances suitable for parenteral application which do notdeleteriously react with the active compounds. Suitable pharmaceuticallyacceptable carriers include, for example, water, salt solutions,alcohol, vegetable oils, polyethylene glycols, gelatin, lactose,amylase, magnesium stearate, talc, surfactants, silicic acid, viscousparaffin, perfume oil, fatty acid monoglycerides and diglycerides,petroethral fatty acid esters, hydroxymethyl-cellulose,polyvinylpyrrolidone, and the like. The pharmaceutical preparations canbe sterilized and if desired, mixed with auxiliary agents, e.g.,lubricants, preservatives, stabilizers, wetting agents, emulsifiers,salts for influencing osmotic pressure, buffers, colorings, flavoringand/or aromatic substances and the like which do not deleteriously reactwith the active compounds. For parenteral application, particularlysuitable vehicles consist of solutions, preferably oily or aqueoussolutions, as well as suspensions, emulsions, or implants. Aqueoussuspensions may contain substances that increase the viscosity of thesuspension and include, for example, sodium carboxymethyl cellulose,sorbitol and/or dextran. Optionally, the suspension may also containstabilizers.

Solvents useful in the practice of this invention includepharmaceutically acceptable, water-miscible, non-aqueous solvents. Inthe context of this invention, these solvents should be taken to includesolvents that are generally acceptable for pharmaceutical use,substantially water-miscible, and substantially non-aqueous. Preferably,these solvents are also non-phthalate plasticizer leaching solvents, sothat, when used in medical equipment, they substantially do not leachphthalate plasticizers that may be present in the medical equipment.More preferably, the pharmaceutically-acceptable, water-miscible,non-aqueous solvents usable in the practice of this invention include,but are not limited to, N-methylpyrrolidone (NMP); propylene glycol;ethyl acetate; dimethyl sulfoxide; dimethyl acetamide; benzyl alcohol;2-pyrrolidone; benzyl benzoate; C₂₋₆ alkanols; 2-ethoxyethanol; alkylesters such as 2-ethoxyethyl acetate, methyl acetate, ethyl acetate,ethylene glycol diethyl ether, or ethylene glycol dimethyl ether;(S)-(−)-ethyl lactate; acetone; glycerol; alkyl ketones such as methylethyl ketone or dimethyl sulfone; tetrahydrofuran; cyclic alkyl amidessuch as caprolactam; decylmethylsulfoxide; oleic acid; aromatic aminessuch as N,N-diethyl-m-toluamide; or 1-dodecylazacycloheptan-2-one.

The compositions of this invention can further include solubilizers.Solubilization is a phenomenon that enables the formation of a solution.It is related to the presence of amphiphiles, that is, those moleculesthat have the dual properties of being both polar and non-polar in thesolution that have the ability to increase the solubility of materialsthat are normally insoluble or only slightly soluble, in the dispersionmedium. Solubilizers often have surfactant properties. Their functionmay be to enhance the solubility of a solute in a solution, rather thanacting as a solvent, although in exceptional circumstances, a singlecompound may have both solubilizing and solvent characteristics.Solubilizers useful in the practice of this invention include, but arenot limited to, triacetin, polyethylene glycols (such as, for example,PEG 300, PEG 400, or their blend with 3350, and the like), polysorbates(such as, for example, Polysorbate 20, Polysorbate 40, Polysorbate 60,Polysorbate 65, Polysorbate 80, and the like), poloxamers (such as, forexample, Poloxamer 124, Poloxamer 188, Poloxamer 237, Poloxamer 338,Poloxamer 407, and the like), polyoxyethylene ethers (such as, forexample, Polyoxyl 2 cetyl ether, Polyoxyl 10 cetyl ether, and Polyoxyl20 cetyl ether, Polyoxyl 4 lauryl ether, Polyoxyl 23 lauryl ether,Polyoxyl 2 oleyl ether, Polyoxyl 10 oleyl ether, Polyoxyl 20 oleylether, Polyoxyl 2 stearyl ether, Polyoxyl 10 stearyl ether, Polyoxyl 20stearyl ether, Polyoxyl 100 stearyl ether, and the like),polyoxylstearates (such as, for example, Polyoxyl 30 stearate, Polyoxyl40 stearate, Polyoxyl 50 stearate, Polyoxyl 100 stearate, and the like),polyethoxylated stearates (such as, for example, polyethoxylated12-hydroxy stearate, and the like), and Tributyrin.

Other materials that may be added to the compositions of the presentinvention include cyclodextrins, and cyclodextrin analogs andderivatives, and other soluble excipients that could enhance thestability of the inventive composition, maintain the product insolution, or prevent side effects associated with the administration ofthe inventive composition. Cyclodextrins may be available as ENCAPSIN®from Janssen Pharmaceuticals.

The composition, if desired, can also contain minor amounts of wettingagents, emulsifying agents and/or pH buffering agents. The compositioncan be a liquid solution, suspension, emulsion, tablet, pill, capsule,sustained release formulation, or powder. The composition can beformulated as a suppository, with traditional binders and carriers suchas triglycerides. Oral formulations can include standard carriers suchas pharmaceutical grades of mannitol, lactose, starch, magnesiumstearate, sodium saccharine, cellulose, magnesium carbonate, and thelike.

Various delivery systems are known and can be used to administer thecompounds or compositions of the present invention, including, forexample, encapsulation in liposomes, microbubbles, emulsions,microparticles, microcapsules, nanoparticles, and the like. The requireddosage can be administered as a single unit or in a sustained releaseform.

The bioavailabilty of the compositions can be enhanced by micronizationof the formulations using conventional techniques such as grinding,milling, spray drying and the like in the presence of suitableexcipients or agents such as phospholipids or surfactants.

Sustained release dosage forms of the invention may comprisemicroparticles and/or nanoparticles having a therapeutic agent dispersedtherein or may comprise the therapeutic agent in pure, preferablycrystalline, solid form. For sustained release administration,microparticle dosage forms comprising pure, preferably crystalline,therapeutic agents are preferred. The therapeutic dosage forms of thisaspect of the present invention may be of any configuration suitable forsustained release. Preferred sustained release therapeutic dosage formsexhibit one or more of the following characteristics: microparticles(e.g., from about 0.5 micrometers to about 100 micrometers in diameter,preferably about 0.5 to about 2 micrometers; or from about 0.01micrometers to about 200 micrometers in diameter, preferably from about0.5 to about 50 micrometers, and more preferably from about 2 to about15 micrometers) or nanoparticles (e.g., from about 1.0 nanometer toabout 1000 nanometers in diameter, preferably about 50 to about 250nanometers; or from about 0.01 nanometer to about 1000 nanometers indiameter, preferably from about 50 to about 200 nanometers), freeflowing powder structure; biodegradable structure designed to biodegradeover a period of time between from about 0.5 to about 180 days,preferably from about 1 to 3 to about 150 days, more preferably fromabout 3 to about 180 days, and most preferably from about 10 to about 21days; or non-biodegradable structure to allow the therapeutic agentdiffusion to occur over a time period of between from about 0.5 to about180 days, more preferably from about 30 to about 120 days; or from about3 to about 180 days, more preferably from about 10 to about 21 days;biocompatible with target tissue and the local physiological environmentinto which the dosage form to be administered, including yieldingbiocompatible biodegradation products; facilitate a stable andreproducible dispersion of therapeutic agent therein, preferably to forma therapeutic agent-polymer matrix, with active therapeutic agentrelease occurring by one or both of the following routes: (1) diffusionof the therapeutic agent through the dosage form (when the therapeuticagent is soluble in the shaped polymer or polymer mixture defining thedimensions of the dosage form); or (2) release of the therapeutic agentas the dosage form biodegrades; and/or for targeted dosage forms,capability to have, preferably, from about 1 to about 10,000 bindingprotein/peptide to dosage form bonds and more preferably, a maximum ofabout 1 binding peptide to dosage form bond per 150 square angstroms ofparticle surface area. The total number of binding protein/peptide todosage form bonds depends upon the particle size used. The bindingproteins or peptides are capable of coupling to the particles of thetherapeutic dosage form through covalent ligand sandwich or non-covalentmodalities as set forth herein.

Nanoparticle sustained release therapeutic dosage forms are preferablybiodegradable and, optionally, bind to the vascular smooth muscle cellsand enter those cells, primarily by endocytosis. The biodegradation ofthe nanoparticles occurs over time (e.g., 30 to 120 days; or 10 to 21days) in prelysosomic vesicles and lysosomes. Preferred largermicroparticle therapeutic dosage forms of the present invention releasethe therapeutic agents for subsequent target cell uptake with only a fewof the smaller microparticles entering the cell by phagocytosis. Apractitioner in the art will appreciate that the precise mechanism bywhich a target cell assimilates and metabolizes a dosage form of thepresent invention depends on the morphology, physiology and metabolicprocesses of those cells. The size of the particle sustained releasetherapeutic dosage forms is also important with respect to the mode ofcellular assimilation. For example, the smaller nanoparticles can flowwith the interstitial fluid between cells and penetrate the infusedtissue. The larger microparticles tend to be more easily trappedinterstitially in the infused primary tissue, and thus are useful todeliver anti-proliferative therapeutic agents.

Preferred sustained release dosage forms of the present inventioncomprise biodegradable microparticles or nanoparticles. More preferably,biodegradable microparticles or nanoparticles are formed of a polymercontaining matrix that biodegrades by random, nonenzymatic, hydrolyticscissioning to release therapeutic agent, thereby forming pores withinthe particulate structure.

The compounds and compositions of the present invention can beformulated as pharmaceutically acceptable esters or salts.Pharmaceutically acceptable salts include, for example, alkali metalsalts and addition salts of free acids or free bases. The nature of thesalt is not critical, provided that it is pharmaceutically-acceptable.Suitable pharmaceutically-acceptable acid addition salts may be preparedfrom an inorganic acid or from an organic acid. Examples of suchinorganic acids include, but are not limited to, hydrochloric,hydrobromic, hydroiodic, nitrous (nitrite salt), nitric (nitrate salt),carbonic, sulfuric, phosphoric acid, and the like. Appropriate organicacids include, but are not limited to, aliphatic, cycloaliphatic,aromatic, heterocyclic, carboxylic and sulfonic classes of organicacids, such as, for example, formic, acetic, propionic, succinic,glycolic, gluconic, lactic, malic, tartaric, citric, ascorbic,glucuronic, maleic, fumaric, pyruvic, aspartic, glutamic, benzoic,anthranilic, mesylic, salicylic, parahydroxybenzoic, phenylacetic,mandelic, embonic (pamoic), methanesulfonic, ethanesulfonic,benzenesulfonic, pantothenic, toluenesulfonic, 2-hydroxyethanesulfonic,sulfanilic, stearic, algenic, β-hydroxybutyric, cyclohexylaminosulfonic,galactaric and galacturonic acid and the like. Suitablepharmaceutically-acceptable base addition salts include, but are notlimited to, metallic salts made from aluminum, calcium, lithium,magnesium, potassium, sodium and zinc or organic salts made fromprimary, secondary and tertiary amines, cyclic amines,N,N′-dibenzylethylenediamine, chloroprocaine, choline, diethanolamine,ethylenediamine, meglumine (N-methylglucamine) and procaine and thelike. All of these salts may be prepared by conventional means from thecorresponding compound by reacting, for example, the appropriate acid orbase with the compound.

While individual needs may vary, determination of optimal ranges foreffective amounts of the compounds and/or compositions is within theskill of the art. Generally, the dosage required to provide an effectiveamount of the compounds and compositions, which can be adjusted by oneof ordinary skill in the art, will vary depending on the age, health,physical condition, sex, diet, weight, extent of the dysfunction of therecipient, frequency of treatment and the nature and scope of thedysfunction or disease, medical condition of the patient, the route ofadministration, pharmacological considerations such as the activity,efficacy, pharmacokinetic and toxicology profiles of the particularcompound used, whether a drug delivery system is used, and whether thecompound is administered as part of a drug combination.

The present invention may be administered in the following doses:internal 1 pg/kg to 10 g/kg; topical 0.00001% to 100%, formulated aspreparations for immediate or sustained release. The dosing regimens ofthe present invention include discrete doses of between 1 and 8administrations per day, acute single dose, and chronic multiple dose,as drip (constant IV or other infusion), or as bolus. The invention maybe formulated with solvent and other agents or compounds.

The present invention also provides pharmaceutical kits comprising oneor more containers filled with one or more of the ingredients of thepharmaceutical compounds and/or compositions of the present invention,including, one or more therapeutic agents described herein. Such kitscan also include, for example, other compounds and/or compositions(e.g., therapeutic agents, permeation enhancers, lubricants, and thelike), a device(s) for administering the compounds and/or compositions,and written instructions in a form prescribed by a governmental agencyregulating the manufacture, use or sale of pharmaceuticals or biologicalproducts, which instructions can also reflects approval by the agency ofmanufacture, use or sale for human administration.

EXAMPLES

A more complete understanding of the present invention can be obtainedby referring to the following illustrative examples of the practice ofthe invention, which examples are not intended, however, to limit theinvention. In the following illustrative examples, fast atom bombardmentmass spectra (FAB MS) were acquired on a MS50-TA mass spectrometer, atWashington University, St. Louis, using a matrix of nitrobenzyl alcoholand lithium ion and xenon gas FAB beam to ionize the samples. Theinstrument is a three sector, EBE design with maximum resolving power of50,000. Mass range at full accelerating potential (8 kV) is about 800Daltons. Low resolution FAB spectra are run at a nominal resolution of1000 and high resolution spectra are run at 10,000 resolution. Accuratemass measurement is accomplished by peak matching technique using analkali metal salt ion as the reference mass.

All solvents and commercial reagents were laboratory grade and used asreceived. The MPthiol-linked chelate esters were tested biologically formaximum tolerated dose (MTD) or LD 50, radioprotection, and as scavengercompounds for glaucoma treatment. The MPthiol was tested as aradioprotectant. Attachment of MPthiol to EDTA or DTPA results inderivatives that are of comparable toxicity to the parent compounds. Thecompounds were prepared in several steps from methoxypolyethene glycol(MP) and the chelate EDTA or diethylenetriaminepentaacetic acid (DTP).

Example 1 Methyl Ester of Methoxypolyethlene Glycol Thiol with EDTA(MPSEDE)

MP was converted to the chloride by reaction with thionyl chloride(Bueckmann et al., Biotech. Appl. Biochem., 9: 258-268, 1987) thence tothe thiol by reaction with thiourea (Urquhart et al Organic SynthesesColl. Vol 3; Homing, E. C.; Ed.; Wiley, N.Y., 1955; pp 363-365) followedby treatment with base, acid, and purified by silica gel chromatography.The thiol was coupled to the EDTA as a thioester usingcarbonyldiimidazole as coupling agent with dimethylformamide solvent(Gais, Angew. Chem. Int. Ed. 16:244-246, 1977), followed by methylesterification of the other carboxyl groups with methanol andcarbonyldiimidazole. The products were purified by silica gelchromatography with elution by a gradient of ethyl acetate and heptane,and characterized by saponification and determination of chelate bycopper chloride titration with pyridylazonaphthol indicator (Blijenberget al, Clin. Chim Acta 26:577-579, 1969), determination of thiol byspectrophotometry with Ellman's reagent (Riddles et al Meth. Enzymol.1983, 91, 49-60), and confirmation of the molecular structure by FABmass spectrometry. All of the analyses were consistent with thestructures shown. A representative mass spectrum of MPSEDE is shown inFIG. 2. The product consisted of the chelate coupled to MPthiol withnumber of ethoxy units from 4 to 9, with M+H and M+ Li peaks shown.

Example 2 Methyl Ester of Methoxypolyethlene Glycol Thiol with DTPA(MPSDTE)

MP was converted to MPthiol using the same process described inExample 1. The thiol was coupled to the DTPA as a thioester usingcarbonyldiimidazole as coupling agent with dimethylformamide solvent(Gais, Angew. Chem. Int. Ed. 16:244-246, 1977), followed by methylesterification of the other carboxyl groups with methanol andcarbonyldiimidazole. The products were purified by silica gelchromatography with elution by a gradient of ethyl acetate and heptane,and characterized by saponification and determination of chelate bycopper chloride titration with pyridylazonaphthol indicator (Blijenberget al, Clin. Chim Acta 26:577-579, 1969), determination of thiol byspectrophotometry with Ellman's reagent (Riddles et al Meth. Enzymol.1983, 91, 49-60), and confirmation of the molecular structure by FABmass spectrometry. All of the analyses were consistent with thestructures shown.

Toxicity Studies

For all biological studies, the substances were dissolved in water andadjusted to pH 7. Preliminary determination of the approximate toxicitylevel of the substances was by intraperitoneal (IP) injection ofincreasing doses into individual Swiss-Webster female mice untiltoxicity was evident. The maximum tolerated dose (MTD) was 2 mmole perkilogram without evident toxic symptoms such as coma, convulsions, ordeath.

Radioprotection Studies

The effect of MPthiol derivatives on radiation lethality was tested.Groups of 12 or more female Swiss-Webster mice were given IP solutionsof the derivatives at a dose of approximately one-half of the maximumtolerated dose. Ten minutes later, pentobarbital (PB) 0.262 mmole/kg wasgiven IP, and twenty minutes after the first injection, the head andneck were irradiated at various doses indicated at time 20 to 50minutes. The irradiation was performed using the Philips RT-250 unitoperated under the following conditions: 200 kVp, 20 mA, 0.2 mm Cu addedfiltration, HVL 0.57 mm Cu, dose rate of 1.834 Gy/min. Mice wereirradiated in groups of 6 or 12, and their heads were arranged within a20×24 cm aperture cone at a 50 cm target-to-skin distance such that alltheir heads were within a 95% isodose. The output of the X-ray unit wascalibrated using a Capintec PT-06C Farmer chamber. Controls receivedonly PB and 0.4 ml normal saline in place of the drug.

The mice were examined for general condition and survival, and themortality noted for each group. Under these conditions the mice diedfrom radiation between 10 and 13 days following exposure. FIG. 3illustrates the percent survival of these mice after the administrationof MPthiol or saline followed by irradiation to head and neck at variousdoses. MPthiol was found to be an effective radioprotectant, with a dosemodification factor comparable with known radioprotectors such asamifostine (Ethyol).

Effect on Surgically Induced Glaucoma

MPSEDE was tested in rats for protection against glaucoma and retinalganglion cell loss.

Rat ocular hypertensive model: Ocular hypertension was induced in 9 maleSpragueDawley rats, weighing between 400 to 500 grams. Under generalanesthesia with acepromazine maleate (12 mg/Kg) and ketamine (80 mg/Kg),IP, and topical proparacaine (0.5%), dissection of the conjunctiva wasmade with fine cuts. To reduce the stimulus for revascularization orneovascularization, dissection of the right eye was limited to the areaimmediately surrounding the vortex veins. Three of four vortex veinswere exposed and ligated using 9.0 nylon sutures. Criterion forinclusion into the study was an intraocular pressure (IOP) increase of 5mm Hg or more when compared to cryosurgical baseline IOP. Within 6weeks, the IOP of all the operated eyes increased at least 5 mm Hgcompared to baseline. National Institutes of Health Guidelines andAssociation for Research in Vision and Opthalmology statement for theUse and Care of Animals were followed in this study.

Intraocular pressure (IOP) Measurements: Prior to initiation oftreatment, baseline IOP was obtained in glaucoma rat models. IOP wasmeasured via a specially modified Goldmann applanation tonometer(HAAG-STREIT, Bern, Switzerland) under sedation. Measurements areaverages of two consecutive readings and were made at the same time ofday and by the same observers.

Measurement of ocular damage: Slit lamp (HAAG-STREIT, Bern, Switzerland)examination was performed to determine any possible ocular damage andchanges in the anterior chamber. Examinations were documented by asemi-quantitative scale which was modified to document signs ofinflammation, conjunctival chemosis/swelling, conjunctival discharge,aqueous flare, fibrin, light reflex, iris, corneal opacity,vascularization and staining (Samudre, S S, Lattanzio, F A Jr.,Williams, P B, and Sheppard, J D, Jr., Comparison of topical steroidsfor acute anterior uveitis, J. Ocul. Phamacol. Ther. (2004) 20:533-47).Prior to examination, rats were sedated with acepromazine maleate (6mg/Kg), and ketamine (40 mg/Kg), plus topical administration of 0.5%proparacaine. Throughout the course of the study, this examination wasperformed by the same group of masked, knowledgeable observers.

In vivo analysis by confocal microscopy: This technique permits repeatedin vivo visualization of cornea and anterior segment for the presence,location and number of inflammatory cells, as well as fibrin,hyper-refractive bodies and changes in epithelial, stromal andendothelial cell morphology. Rats were examined under acepromazine (12mg/Kg) and ketamine (80 mg/Kg) anesthesia, plus topical administrationof 0.5% proparacaine using an Advanced Scanning Limited confocalmicroscope (ASL 1000, Advanced Scanning Limited, New Orleans, La.),documented using a CCD camera (Kappa Optoelectronics Inc., Monrovia,Calif.) and recorded with SVO-9500MD VCR (Sony Corporation, Tokyo,Japan). Data was analyzed using Metamorph™ imaging system (UniversalImaging, Downingtown, Pa.).

NMDA retinal damage model: Changes in electroretinogram (ERG) A and Bwaves have been used as indicators of RGC damage. To examine RGCneuroprotection, 2 ul intravitreal injections of 10 mM NMDA, sufficientto change ERG A and B-waves within 2 weeks, were challenged withco-administered intravitreal (2 mM) or topical 100 mM MPDTE, MPSEDE andamifostine in normal rats unilaterally. For topical administration, ratswere pretreated for 5 days prior and 3 days post-NMDA administrationwith the agents at a frequency of 3 times per day with 20 μl agent.Scotopic ERG changes were measured in normal rats. Rats were darkadapted for at least 4 hrs. Eyes were dilated with atropine after whichproparacaine and methylcellulose gel were applied topically. Custom madeAgCl electrodes (64-1317, Warner Instruments, Hamden, Conn.) were placedon the apex of the cornea. Stimuli consisted of 10-microsec flashes ofunattenuated white light generated by Ganzfield bowl photo stimulator(Grass Instruments, PS22, Quincy, Mass.). Data from each eye wasrecorded separately with a driver amplifier (Grass Instruments, Model7DAF Polygraph, Quincy, Mass.). Data was acquired digitally via DASYLab(Bedford, N.H.). The contralateral normal eye served as an age matchednegative control, e.g. response in a normal, undamaged eye. Differencesin amplitude of the A-wave and B-waves between the treated eye and thecontralateral eye and between treatment groups were calculated.

Topical application of MP compounds for IOP measurements on rat surgicalglaucoma model: Rats were treated topically with 20 μl of MP compounds(0.3-100 mM; n=3-6) on the operated eyes. The MP compounds were comparedto 10 or 87 mM topical amifostine, a free radical scavenger. MPesterified chelators were diethylenetriaminepentaacetic acid (MPDTE) andMPSEDE.

Chronic test of MPDTE ocular toxicity: Two groups of normal rats weretested with 20 μl topical doses in one eye of 10 mM MPDTE (n=3) or 87 mMMPDTE (n=3) with 3 daily doses for 1 month. IOP, slit lamp and confocalexaminations were done prior to drug administration a slit lampexamination at 15 days and IOP, slit lamp and confocal examinations 30days later.

Pharmacokinetic experiments: To determine topical absorption andsystemic distribution of MP compounds, ¹⁴C-labeled MPDTE wasadministered to normal rats in a 20 μl drop of 30 mM MPDTE. The ¹⁴Clabel was attached to the MP backbone to reduce the chance of spuriousexchange. After 15-120 minutes with 2-6 animals per time point, theanimals were euthanized and blood, urine and tissue samples wereobtained. The eyes were enucleated and rinsed 5 times with 0.9% salineto remove unabsorbed drug. Samples were solubilized and counted in aliquid scintillation counter to determine the presence of theradiolabeled MP.

Data Analysis: One Way Analysis of Variance used to analyze IOP, bloodpressure and heart rate data. The paired t-test was used for pair wisecomparisons. Non-parametric data were analyzed by the signed ranks test.A difference of P<0.05 was considered statistically significant. Allvalues reported as mean ±SEM unless otherwise noted.

Doxorubicin Chemotoxicity Studies on H9C2 Cells

H9C2 cells, which are used as models for rat striated muscle, werecultured using techniques described previously (Lattanzio, F A Jr.,Tiangco, D., Osgood, C., Beebe, S., Kerry, J. and Hargrave B Y. Cocaineincreases intracellular calcium and reactive oxygen species, depolarizesmitochondria, and activates genes associated with heart failure andremodeling. Cardiovascular Toxiology (200505: 377-389). Fluorescentcalcium indicator and ROS indicator were used to determine if thereported increase in intracellular calcium and ROS activity occurred andwhether these changes were reduced in the presence of 2 mM MPSEDE orMPDTE. Cells were measured using a Zeiss 510 fluorescent confocalmicroscope as described in Lattanzio et al, 2005.

FIG. 4 demonstrates penetration of MP compounds into the globe in ratswith topical ocular administration but with very little crossover intothe untreated contralateral eye or the brain (brain data not shown).Elimination of MPDTE is primarily through the urine. Chronic topicaldosing of normal rats showed no ocular toxicity in either eye asdetected in slit lamp or confocal examinations after one month and noresidual change in IOP.

Initial testing of MPDTE and MPSEDE demonstrated that a single dose of10-100 mM significantly reduced IOP (FIG. 5, FIG. 6, FIG. 7). The MPDTEand MPSEDE dose-response curve at 60 minutes, near the peak of most ofthe topical MP IOP responses, is shown in FIG. 8. The IOP reductioncaused by MPDTE could be maintained for ˜2 hours with a single dose andis compared with the experimental cannabinoid (1% WIN 55,212-2) oramifostine in FIG. 9. No reduction in IOP was seen with 10 mM or 87 mMamifostine.

The mechanism of reduction in IOP was explored by comparing theindividual and combined effects of the MP backbone and the effects ofthe chelator group DTE. As seen in FIG. 10, there is a reduction in IOPwhen either MP or DTE is administered alone or together, but the IOPreduction was not as great as with MPDTE.

Co-administration of MPDTE with NMDA significantly maintained A-wave(FIG. 11) and B-wave (FIG. 12) amplitudes, respectively, in comparisonto the reductions seen with NMDA alone. MPSEDE showed a trend to reduceNMDA damage, but this was not significant at the dose tested. Bothintravitreal and topical administration of either MPSEDE or MPDTEsignificantly reduced NMDA damage (Table 1).

TABLE 1 Intravitreal Topical % Baseline A/B wave A/B wave NMDA 51.2/68.451.2/68.4 NMDA + MPDTE 90.0/90.0 82.5/88.1 NMDA + MPSEDE 76.2/69.695.9/93.7 NMDA + Amifostine 94.2/83.3 69.4/99.3

Chemoprotection

H9C2 cells, a rat myocyte model, were cultured in MEM until confluentusing techniques described in Lattanzio et al, 2005. The cells weretreated with 5 μM fluo-3 μM, a fluorescent calcium indicator, for 30 minat 37 C, washed and then exposed to 50 μM doxorubicin (a supermaximaltoxic dose), in the presence or absence of 30 min pretreatment with 2 mMMPDTE. Doxorubicin increases intracellular calcium in cardiac cells bydisrupting calcium homeostasis through the production of free radicaldamage and subsequent membrane damage. After a 10 min exposureintracellular calcium increased 59.4% in untreated cells, but only 40.2%in MPDTE treated cells (p<0.001 for n=20 cells in 3 separate trials).Protection may have occurred due to a combination of free radicalscavenging and calcium chelation.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of the present invention and,without departing from the spirit and scope thereof, can make variouschanges and modifications of the invention to adapt it to various usagesand conditions.

1. A methoxypolyethylene glycol thioester compound of formula (I):

wherein one R₁ is formula (II)

each of the remaining R₁ is selected from formula (II) or from the groupconsisting of —CH₂COOH, —CH₂COO⁻Na⁺, —CH₂COO⁻Ca⁺⁺/2, —CH₂COOCH₃,—CH₂COOC₂H₅, and —CH₂COOC₃H₇; a is 0 to 6; each b is independently 0 to18; each c is independently 3 to 10; and d is independently1 to
 3. 2.The compound according to claim 1, wherein a is 0, each b is 0, each cis independently 3 to 10, d is 1, and three R₁s are —CH₂COOCH₃.
 3. Thecompound according to claim 1, wherein a is 1, each b is 0, each c isindependently 3 to 10, d is 1, and four R₁s are —CH₂COOCH₃.
 4. Thecompound according to claim 2, wherein each c is independently 7 or 8.5. The compound according to claim 3, wherein each c is independently 7or
 8. 6. The compound according to claim 1, wherein the compound is

wherein n=3 to
 10. 7. The compound according to claim 1, wherein thecompound is

wherein n=3 to
 10. 8. The compound according to claim 1, wherein thecompound is capable of extracting electrons.
 9. The compound accordingto claim 1, wherein the compound is capable of forming chelates withheavy metals or Ca⁺⁺.
 10. A composition comprising the compound of claim1 and at least one of a pharmaceutically acceptable carrier or apharmaceutically acceptable adjuvant.
 11. A composition comprising thecompound of claim 2, 3, 6, or 7 and at least one of a pharmaceuticallyacceptable carrier or a pharmaceutically acceptable adjuvant.
 12. Acomposition comprising at least one compound of claim 1 or apharmaceutically acceptable salt or solvate thereof, and, optionally, atleast one therapeutic agent.
 13. The composition of claim 12, furthercomprising at least one of a pharmaceutically acceptable carrier or apharmaceutically acceptable adjuvant.
 14. A method for protecting tissueagainst damage resulting from exposure to radiation in a patient in needthereof comprising administering to the patient a therapeuticallyeffective amount of the compound of claim 1, 2, 3, 6, or
 7. 15. A methodfor treating retinal cell death resulting from glaucoma in a patient inneed thereof comprising administering to the patient a therapeuticallyeffective amount of the composition of claim
 10. 16. A kit comprising atleast one compound of claim 1, 2, 3, 6, or 7, or a pharmaceuticallyacceptable salt or solvate thereof, and instruction for use thereof. 17.A method for extracting electrons from free radical oxidants in a cellin need thereof comprising administering an effective amount of thecompound of claim 1, 2, 3, 6, or 7, wherein the free radical oxidantsare selected from the group consisting of peroxides, superoxide anions,hydroxyl radical, and nitric oxide.
 18. A method for mitigatingcatalysis of free radical oxidants formation by heavy metals in a cellin need thereof comprising administering an effective amount of thecompound of claim 1, 2, 3, 6, or 7, wherein the free radical oxidantsselected from the group consisting of peroxides, superoxide anions,hydroxyl radical, and nitric oxide, wherein the compound is capable offorming chelates with heavy metals.